ABSTRACT
For many years, the classification of regular tachycardia at the atrial level has been based exclusively on the electrocardiogram (ECG). As a historical legacy, the term “flutter” was reserved only for fast rhythms without an isoelectric line between two atrial deflections. The incidence of these arrhythmias, especially of atypical atrial flutter, has grown with the widespread deployment of atrial fibrillation ablation. Typical atrial flutter is macro-re-entry around a central obstacle composed of the orifices of the inferior and superior vena cava, posteriorly by the crista terminalis or the sinus venosus and the Eustachian ridge and limited anteriorly by the tricuspid valve. In many cases, the Eustachian valve and ridge form a line of conduction block between the inferior vena cava and the coronary sinus ostium. Atrial flutters have characteristic ECG morphologies which should be used for an accurate diagnosis. A systematic approach is key to successful ECG-based diagnostic of the origin of atrial flutters.
